Different type of cell shapes in FEA

Different type of cell shapes in FEA

We will use different type of cells in computational studies some of them are two dimensional and others are three dimensional. Lets have a look at them in a little brief

Two - Dimensional

We will commonly use two types of two-dimensional cells shapes they are triangle and quadrilateral.

Triangle

This type of elements having 3 edges and we can consider it as one of the simplest cell type. most of the cases 2d elements are called surface meshes. It is easy to create and mostly used in Un structured mesh type.

First order elements having 3 nodes and second order elements having 6 nodes.

First Order Element

                                Unstructured Traingle                                           Second Order Element

Quadrilateral

These elements having basic four sides commonly used in Structured mesh. First Order Elements having 4 nodes and Second order elements having 8 nodes.

                                                  
                                                                 Structured Mesh

Three - Dimensional 

The basic 3 Dimensional element are the tetra hedron, Quadrilateral Pyramid, Traingular Prisam and hexa hedron. These all having traingular and quadrilateral faces. Prism and Hexa hedra are extruded models of traingle and quadrilaterals.

Tetra Hedran

A tetra hedron has 4 vortices, 6 edges and 4 traingular faces. This can be generated autometically while meshing 3D Volumes.

Tets First order and Second order

Pyramids

Pyramid elements has 5 nodes 8 edges, 4 traingular faces and one quad face. It is mainly used as a conecting element between Quads and traingles. Mostly used in Hybrid Mesh Type.

First order and second order Pyramids

Trangular Prism

A trainglular prism have 6 vertices, 8 edges and 2 trangular faces, 3 Quadri lateral faces. This type if meshes are more efficient in Boundary layer problems.

Hexa Hedron

These cells are called as Cubes also. This cells has 8 nodes, 12 edges, 6 Quadrilateral faces. These are the acuurate mesh cells mostly used in Structured mesh.

First order and second order Hexa Hedra

Poly Hedron

These are the Advanced cells in all the types. This cells might have any number of nodes nad edges so it consumes more computation time but gives more accuracy

Classification Of Mesh Grids

Classification Of Mesh Grids

Structured Grids

A Structured grid having regular connectivity with the surrounding elements. we can achieve structured grid by using 2D quadrilateral and 3D Tetrahedra this model requires less space due to its proper storage arrangements due to it shape.

Eg:-

Advantages

1. Better Convergence 
2. Higher Resolution
3. Results Accurac
4. Data Locality
5. Available solution Algorothims
6. High degree of control

Challenges

1. More time to create

Unstructured Grids

An unstructured grids can be identified by its irregular conectivity to its surrounding elements. It is bit difficult to represent in 2 dimensional or 3 dimentsional in computer memory. When compared to structured grids it consumes more space because of its explicit storage of neighborhood relationship. we can achieve this grids by using Traingles in 2D, tetrahedra in 3D.

Eg :-

Advantages

1. Less Time to create
2. Complex Shapes can be meshed

Challenges

1.  less Accuracy in results if we choose improper element size

Hybrid Grids

It is a combination of structured and unstructured grids it can integrate structured mesh and unstructured mesh in an efficient manner. we can choose which type of grids can be used based on the model shape if it s simple we can opt for structured grids if model is complex shape we can opt for n structured grids. these grids are non con formal means this grid lines no need to match with block boundaries.

Eg :-

Advantages

1. Accuracy and Time can be managed as per the Time Availablity